Mix of #ifdef and macro invocation in preprocessor

I have a very strange behaviour with my WIP port of pcc, and I do not believe this is related to my modifications, neither I think the behaviour of pcc is correct.

I reduced the case to the attached snippet; I hope it is self explaining.

Description

I have a very strange behaviour with my WIP port of pcc, and I do not believe this is related to my modifications, neither I think the behaviour of pcc is correct.
I reduced the case to the attached snippet; I hope it is self explaining.